The newly-announced iPhone 4 adds a 3-axis gyroscope to the motion-sensing mix, tied together with the accelerometer and built-in GPS to provide 6-axis motion sensing gaming.

In these pictures from gdgt, Steve Jobs introduces an all-new method of motion controlling iPhone games live on stage at Apple's WDCC 2010 event.

Previous iterations of the iPhone have used an accelerometer to sense side-to-side and up-and-down movement, which has worked fine so far. The iPhone 4 adds a gyroscope to the mix, giving the device full 3D motion support. Jobs demonstrated this using a Jenga-like tower of blocks, which he tilted and rotated until they finally toppled over.

"We've tied the gyro, accelerometer, and GPS for 6-axis motion sensing. It's perfect for gaming - and one of the reasons it's perfect is because it's built into every iPhone 4, so you know it's there."

In essence, this development will allow for full motion-controlled gaming on a mobile platform. This could be big.